A 16-year-old male patient suffers from malignant Chronic Suppurative Otitis Media (CSOM) with subperiosteal abscess complication. The patient has a history of intermittent discharge from the right ear, since his age of 9 years old and never received any treatment. Ear examination was normal in the left ear. In the right ear, the external acoustic canal is narrow, there is no discharge and the tympanic membrane is difficult to evaluate. Examination of the nose revealed no abnormalities. The throat examination revealed no abnormalities. In the right temporoparietal region, there was a lump measuring 9x8 cm, redness, tenderness, warmth and fluctuating. In this patient, incision and drainage were performed. Furthermore, we did dilatation and drainage of the abscess every day until no pus is formed. After that, it was followed by a right canal wall-down mastoidectomy. Intraoperatively, cholesteatoma, granulation, and pus were found in the mastoid cavity, antrum, and tympanic cavity, closing the orifice of the Eustachian tube. Destruction of the incus, scutum, and posterior wall of the external acoustic canal. Perforated tympanic membrane. Tissues suspected of cholesteatoma were examined for anatomic pathology. From the results of anatomical pathology, histomorphology was found to be suitable for cholesteatoma. The principle of therapy for the malignant types of CSOM (with cholesteatoma) is surgery for cholesteatoma eradication and reconstruction. Treatment of subperiosteal abscess includes intravenous antibiotics, incision and drainage of the abscess, and mastoidectomy.